The present invention relates generally to wheeled vehicles, in the nature of heavy duty apparatus used for construction, earth working, earth moving and the like.
More specifically, the invention relates to a brake system, operatively mounted in the interior of a wheel incorporating a final drive in wheel loader vehicles, and the like, of substantial size, having large wheels thereon. The vehicles normally are moved at relatively slow operational speeds, but have high momentum forces created, and which must be overcome in braking and stopping such vehicles.
In vehicles of the type to which the present invention is applied, wheel final drive assemblies and braking systems for the vehicle have heretofore been incorporated positionally and operationally within a vehicle wheel hub. The brake systems in these vehicles have included oil flooded disc brake types. A brake system of this type is disclosed in U.S. Pat. No. 3,301,359, dated Jan. 31, 1967, entitled Braking Apparatus, and owned by the assignor of this application.
The braking mechanism and system disclosed in that patent, and other known similar systems, while proving effective in some vehicles, have disadvantages when used in vehicles of greatly increased size and weight, wherein the forces which must be overcome in braking of the vehicle require substantially greater braking forces and strengths. This has led to consideration of plural disc pack arrangements by the assignor company of this application, one structure of which is shown and described in detail in a copending application of the present inventor entitled a Double Disc-type Brake System, Ser. No. 879,306, filed Feb. 21, 1978, and assigned to a common assignee herewith.
In brake systems of the type disclosed in the aforesaid copending patent application, the braking arrangement in essence constitutes a double, back to back, disc pack arrangement, the actuating means being serially operable to initially actuate one disc pack, following an initial incremental actuation of the brake energizer or pedal, and subsequently, upon additional energization or movement of the pedal, initiating and implementing braking action in a second disc pack. This arrangement overcomes in part braking problems which arise in large and heavy wheeled units.
In some known systems, as also in the systems involved in larger and heavier vehicles of the type shown and described herein, additional problems have arisen, a very substantial one of which involves cooling and lubricating of the brake systems, and primarily the brake disc packs within the wheel of the wheel loader final drive. The larger the vehicle, the greater the force required to brake it, and the greater heat factor to be overcome.
Disc brakes of the type involved are normally of an oil flooded disc brake type, and the disc packs are enclosed within cavities or areas where it is difficult to circulate the cooling and lubricatng oils in adequate oil flow past the disc packs, without using external pumping means or the like.
It is an important object of the present invention to eliminate, insofar as possible, drawbacks existant in prior known and used apparatus.
Another important object of the present invention is to provide, in an oil flooded disc brake enclosed within the wheel of a wheel loader final drive, means to increase the oil flow internally so as to more effectively circulate the lubricating and cooling oil through and within cavities, and in such quantities past the disc packs, as to insure functional cooling and lubrication.